Hard disc drives (HDDs) typically comprise one or more magnetic media discs or other magnetic storage media, each having concentric data tracks for storing data. Where multiple discs are used, a stack is formed of co-axial discs having generally the same diameter. A transducing head carried by a slider is used to read from and write to a data track on a given disc. The slider is connected to a suspension assembly, which can include a load beam and a gimbal, and the suspension assembly is in turn attached to an actuator arm. The load beam is generally made of a metallic material, typically stainless steel. The gimbal can be a separate metallic element secured to the load beam to support the slider thereon while permitting some movement of the slider, and can also be made of stainless steel. During operation, as the disc spins, the slider glides above the surface of the disc on a small cushion of air. The actuator arm pivots to movably position the slider with respect to the disc. A microactuator assembly can be included to provide additional precision positioning of the suspension assembly. Electrical connections extend along the suspension to electrically connect the transducing head to components located at or near the actuator arm. Those electrical connections can be formed on the suspension itself, or can be located on a separate interconnect structure supported relative to the suspension, such as a flex-on suspension (FOS).
Magnetic storage media can store data as bits with magnetization directions in-plane, or perpendicular to a plane of the media. Greater storage densities can generally be achieved with perpendicular recording.
The transducing head typically includes a writer and a reader. The reader includes a sensor for retrieving magnetically encoded information stored on the disc (or other magnetic storage medium). Magnetic flux from the surface of the disc causes rotation of the magnetization vector of a sensing layer or layers of the sensor, which in turn causes a change in the electrical properties of the sensor that can be detected by passing a current through the sensor and measuring a voltage across the sensor. Depending on the geometry of the sensor, the sense current may be passed in the plane (CIP) of the layers of the sensor or perpendicular to the plane (CPP) of the layers of the sensor. External circuitry then converts the voltage information into an appropriate format and manipulates that information as necessary to recover information encoded on the disc.
The writer, for a perpendicular recording transducing head, typically includes a main pole and a return pole, which are separated from each other at an air bearing surface (ABS) of the transducing head by a gap layer. The main pole and return pole can be connected to each other at a region distal from the ABS by a back gap closer or back via. One or more layers of conductive coils are positioned between the main and return poles, and are encapsulated by electrically insulating layers. The conductive coils can have different configurations, such as helical and pancake configurations. To write data to the disc (or other magnetic storage medium), an electric current is applied to the conductive coils to induce a magnetic field in the disc under a pole tip of the main pole. By reversing the direction of the current through the coils, the polarity of the data written to the magnetic storage medium is reversed, and a magnetic transition is written between two adjacent bits of the magnetic storage medium.
The slider includes a slider body (typically called the “substrate”) and an overcoat that includes the transducing head. The slider body and the overcoat are typically made of a ceramic material. A plurality of bond pads are formed on the slider, such as at a trailing edge or top surface of the slider, for electrically connecting elements of the transducing head to external circuitry through the overcoat.
During fabrication and operation of a HDD, particles can be generated. The presence of particles in an HDD, particularly metallic particles, is undesirable, and can cause a decrease in HDD performance. One particular problem is that particles can accumulate on surfaces inside the HDD and later shed to the magnetic storage media, increasing a risk of unwanted magnetic erasures. Modern HDDs are much more sensitive to particles than previous-generation HDDs. While there are known solutions for capturing particles and limiting negative effects of particles present within HDDs, it is desirable to limit the creation of particles rather than merely redress the presence of particles already created.